With the development of semiconductor technology, packaging technology and the like, the power density of power modules is increasingly larger and the conversion efficiency is increasingly higher, and hence the reasonable and effective layout of various components on a printed circuit board (PCB) is more and more important. A power system tends to need a plurality of independent DC-DC power modules and various modules are required to not only output independently but also operate in parallel. POL power module is one of the DC-DC power modules. As the modular layout has a plurality advantages, the power module is widely applied in the communication field such as interchangeable equipment, access equipment, mobile communication, microwave communication, optical transmission and router and the fields such as automotive electronics and aerospace. An inductor element usually has largest volume and heaviest weight in the DC-DC power module, so that the structure and the layout of the inductor can directly have effect on the positions of other components.
How to design a DC-DC power module with high efficiency and reasonable device layout becomes one of the most important problems to be solved currently.